The invention is related to holographic optical device constructions. More specifically, the invention relates to reducing environmental impact to the holographic recording media of the optical device. Even more specifically, the invention relates to sealing the peripheral edges of a pair of substrates in a holographic recording device.
As the need for storage of more and more massive amounts of data has continued to increase, the use of holographic optical recording medium and techniques has gained attention. In general, holographic recording techniques for recording information in a recording medium employ generation of interference fringes. The interference fringes are written three-dimensionally inside the recording medium by superposition of information light (e.g., carrying image information) and reference light. The information is recorded in the form of the interference fringes. For the purpose of playing back or reading the information, reference light is applied to the recording medium where it is diffracted by the interference fringes. The image information is reproduced in the form of the diffracted light.
Various photopolymers are being developed to act as the recording layer in these holographic optical recording systems. A drawback of many of these photopolymer recording layers is that the environment negatively affects them. That is, exposure of these photopolymers to air and moisture results in degradation of the photopolymer. More specifically, such degradation comes in the form of reduced dynamic range of the photopolymer and hence reduced storage of data. Environmental exposure, specifically moisture, can also result in swelling of the photopolymer.
It is desired to provide a holographic optical device construction in which the photopolymer layer is protected from the environment.
A holographic optical data storage device is provided according to the invention. The holographic optical data storage device includes a photopolymer layer having an upper surface and an oppositely disposed lower surface. The device further includes a substantially transparent upper substrate layer having a first inside surface lying adjacent to the upper surface of the photopolymer layer. The device further includes a substantially transparent lower substrate layer having a second inside surface lying adjacent to the lower surface of the photopolymer layer. The upper and lower substrates have first and second peripheral edges respectively with an opening formed therebetween. The device further includes a connection member engaged to the upper and lower substrates wherein the connection member seals the opening, wherein exposure of the photopolymer to the environment is reduced.
A holographic optical data storage device is provided according to the invention. The holographic optical data storage device includes a photopolymer layer having an upper surface and an oppositely disposed lower surface. The device further includes a substantially transparent upper substrate layer having a first inside surface lying adjacent to the upper surface of the photopolymer layer. The device further includes a substantially transparent lower substrate layer having a second inside surface lying adjacent to the lower surface of the photopolymer layer. The upper and lower substrates have first and second peripheral edges respectively. The device further includes means for sealing the first and second edges wherein exposure of the photopolymer to the environment is reduced.
A method of making a holographic optical data storage device is provided according to the invention. The method includes providing a substantially transparent upper substrate having a first inside surface and a first peripheral edge. The method further comprises the step of providing a substantially parallel and transparent lower substrate having a second inside surface and a second peripheral edge, wherein an opening is formed between the first and second edges. The method includes the step of injecting a photopolymer layer between the first inside surface and the second inside surface wherein the photopolymer layer lies adjacent to the first inside surface and the second inside surface. The method further includes curing the photopolymer. The method further includes providing a connection member, wherein the connection member seals the opening.